Gasoline manufacturing process



Feb. 25, 1936. ,J. K. ROBERTS El AL I GASOLINE MANUFACTURING PROCESSFiled March 50, 1934 m NN Q LmEKSm NW mm QQEm 5 386% In 0 enters QJosep/zjckoberw N Morris Z'arpe/zter I I I a l. ATTORNEY Patented Feb.25, 1936 UNITED STATES PATENT OFFICE GASOLINE MANUFACTURING PROCESSJoseph K. Roberts and Morris '1'. Carpenter, Hammond, Ind., assignors toStandard Oil Company, Chicago, 111., a corporation of Indiana Thisinvention relates to a process of manufacturing gasoline and moreparticularly gasoline derived, to a large extent, from the so-calledcracking process. One of the objects of the invention is to produce twogrades of gasoline for use in diiierent seasons, specifically, a summergrade for use in warm weather and a winter grade for use in coldweather. Formerly it was the practice to use the same grade of gasolinefor all seasons but it has more recently been found desirable to marketa more volatile grade of gasoline during the winter season than duringthe summer season. Higher volatility is required in cold weather inorder to obtain better starting and warming up characteristics ingasoline engines resulting from more nearly complete vaporlzation of thegasolinein the colder induction system. The volatility ofsummerga'soline, on the other hand, is limited by the consideration 20of vapor lock which occurs when the vapor pressure of the motor fuel issufliciently high to interfere with proper carburetion. A mostconvenient indication of the suitability of the gasoline in use inwinter is the percent distilled of! 25 at 158 F. in an Englerdistillation. The suitability of a summer gasoline for use without vaporlocking trouble is best expressed by the Reid vapor pressure describedas A. S. T. M. Tentative Standard-D 323-32T.

30 A specific object of this invention is to produce from a given sourceof supply of gasoline a winter gasoline having a maximum volatility asmeasured by percent of! at 158 F. and a summer gasoline having a minimumtendency to vapor locking as measured by the Reid vapor pressure. Astill further object of the invention is to produce such winter andsummer gasolines from a gasoline stock of substantially unvaryingcomposition without adding or discarding any 40 valuable componentthereof.

The invention will be readily understood by reference to theaccompanying drawing which shows diagrammatically a. plant suitable forcarrying out the necessary operations. Referring -15 to the drawing, agasoline supply is indicated by tank I which may contain stabilized endpoint gasoline produced by a cracking process or a blendof crackedgasoline and virgin gasoline from crude distillation. Gasoline iswithdrawn so from supply tank [by line 2 and pump 3 to fractionator lwhere it is subjected to rectification by heat which is supplied torebelling coil 5. The purpose of this rectification is to remove fromthe gasoline a substantial part the butane and mnmne' fractions. Thebutane fraction is with.

drawn from the fractionating column in the form of vapor and passed byvapor line B to condenser I. The liquefied butane is collected inreceiver 8 from whence it is discharged by line 9 through valve In andinto butane storage tank II. The fractionator 4 is preferably operatedunder suflicient pressure to obtain condensation of the butane vapors inthe condenser I at ordinary cooling water temperatures. A pressure of50-75 lbs. gage is sufllcient for this purpose. A reflux 10 coil l2,disposed in the topof the fractionator, supplies the necessary refluxliquid for obtaining separation of the butane from the heavierconstituents in the gasoline, or an outside reflux condensation systemmay be provided. From an intermediate point in the fractionator I thereiswithdrawn by line l3 a second fraction consisting largely of pentanes.This stream is introduced into side stripper supplied by heat from re-'boiler coil l5 where butanes are separated from this fraction andreturned, in the form of vapors, to the main rectifier by line It. Thesubstan- I tially butane-free pentanes are discharged by line H throughcooler l8 and into pentanestorage tank IQ.

From the base of the main fractionator 4 there is withdrawn by line 20the remainder of the gasoline free from butanes and substantially freefrom pentanes. After passing through cooler 2| this stock is introducedinto storage tank 22 where it is retained until further required forblending, as will hereinafter be described. Simultaneously with theoperation of fractionator 4,-another stream of gasoline from supply tankI or other source may be passed by line 23 to fractionator 24 which issimilar to fractionator 4 and operated under substantially the sameconditions of temperature and pressure. Heat is supplied by reboilercoil 25 to efiect satisfactory rectification in. this column andrefluxing is obtained by supplying a cooling fluid to reflux coil 26 ora portion of the distillate may be returned for this purpose. Butanevapors withdrawn by line 21 pass to condenser 28 and thence to'receiver29, whence condensed butane is discharged by line 30, valve 3|, and line9 into butane storage tank H. The pressure in storage tank ll may bemaintained substantially atmospheric by means of suitable heatinsulation surrounding the tank and refrigerating means to maintain thecontents of the tank at a sufilciently low temperature to preventexcessive loss by evaporation in any season, or if desired, the contentsof tank ll maybe held under slight pressure. 1 Gasoline which may besubstantia1ly butanefree is withdrawn from tower 24 byline u to iswithdrawn from tank 34 by pump 42 and line 43 to mixer 44 where it isblended with pentane removed from tank I! by pump '45 and line 48; aftermixing in mixer 44, the resulting stock is transferred by line 41 togasoline storage tank 40. Ordinarily the'desired amount of butane willbe obtained in the winter gasoline by allowing some butane to remain inthe gasoline from supply tank I. In order to obtain increasedflexibility, however, butanes maybe withdrawn from tank II by pump 38,line 39, valve and line II to mixer 44 where they are blended-with thewinter gasoline stock in. the desired amount.

. It should he understood that in the foregoing discussion the termsbutane and pentane. are used to describe stocks comprised chiefly ofthese hydrocarbons and that for practical operation these stocks willcontain a certain percentage of other hydrocarbons closely related inboiling point; for

example, the butane fraction may contain from 25 to 30% of pentanes,whereas the pentane fraction may convenientlycontainfrom 15 to 20% ofbutanes on the one hand and 15 to 20% of hexanes on the other. It isobviously not essential to separate from the gasoline pure butanes 'andpentanes for blending purposes.

The composition of-the fractions which are produced' will natm'ally beconsideredwhen calculating the proportions to use in subsequent blends.I

In a typical operation, cracked gasoline which has been stabilized toremove substantially all of the undesired wild" hydrocarbons presentsthe following analysis: 7

Heavier oonstitnents Percent oil at 158 F.

' Butanes Pentanee m 411% mesa; 11.5% -78.0%' 10.8lbe. .22.

One part oi'this stock gasoline is fractionated 1h tower 4, removingtherefrom substantially all the butanes or 10.35% of the gasoline, and alarge part of the pentanes as required, in this case 10.9% of thegasoline. Another portion of the stock, in this case an equal volume, isfractionated in tower 24 where a substantial amount of its butanecontent is removed, for example 5% of thestock. 1 v V v In preparing thedesired summer and'winter gasoline, suiiicient butane from tank] I isblended with gasoline from tank 22 to produce a summer gasoline ofapproximately the following composit n: '1

Heavier Reid Pceent Propane Butanm' Pnntanu constit- -ofl at uents W 158F.

0.1% an, -'a1% i 85.9% aims. 11.0

n will be noted that the We of butanea in' purposes, as herethisgasoline exceeds the amount of pentanes by 11.9% and that the midof-pentane to butane is 0.76. v a

In making the winter gasolinesuiilcient pen- "time is withdrawn fromtankl! and blended with gasoline from tank 34 to produce a wintergasotion: g

Heavier Percent Reid vapor Propane Butanes Pentanee cagisltuit pmum lagr}:

c193 12 8% 11% 10.1% 12. o lbs. 40

In the above analyses the term propane is inline having approximatelythe following compositended to include both propane and propylene,

the term butane includes all the four carbon atom hydrocarbons presentin the gasoline and the term pentane includes all the five carbon atomhydrocarbons present.

Another example of our invention is illustrated in the following table:

Exampl 2 .Geeoline Summc Winter gasoline gasoline Still another exampleof our invention is shown in the following table;

Emmple: v

decline Hummd Wintc stock gasoline moiine 'oti 0.1 0.! 10.3 10.5 10.012.4 1.5 29.0 7-7.2 87.9 81.9

It will be noted that the ratio of pentane to butane in the. summer andwinter gasolines dif-' fers very greatly. In the Examples 2 and 3 thisratio'in summer gasoline is only 0.11 and 0.14 respectively, whereas inwinter gasolines the ratio is 3.6 and 2.9. This ratio is characteristicof our winter and summer g 'andis always lower 7 for the summergasolinethanfor'the winter gasoline. It will be noted amount of butanein the gasoline-exceeds the amount of pentane by 9% in this example.

Fromtheseanalyse'sitwillbeobservedthat starting with a stock which issatisfactory neither forwinternorsmnmerusebecauseitis oftoolowvolatility for winter and too high Reid vapor pressure for summer, wehave produced a winter and summer gasoline suited for the requirementsof these This is accom-. -plished principally by the novel expedient ofremoving a large part or the pentane fraction from Vthesummergasolinestockandadding'ittothe winter gasoline stock, at thesame time replacing the'pentanes removed from the gaso-- line stock-bybutanes. 'Iheresult is a winter gasoline of high volatilityandjrelatively low va-' por pressure, owing itsivolatility largely topentanes; and a summer gasoline of relativelyJow volatility but vetquite satisfacixrv for summer gasoline over ordinary gasolines owingtheir vol-' atility largely to pentanes and heavier hydrocarbons lies inits lower tendency to vapor lock in hot weather when compared withordinary summer gasolines having the same Reid vapor pressure. Thisadvantage is apparently due to the loss of butane which occurs inhandling in hot weather and which has a greater influence inlesseramount of vapor is formed, thereby resulting in less trouble or vaporlock, inasmuch as the relation of vapor pressure to percent evapofatedis represented by a steeper curve than in the case of ordinary summergasolines depending for their volatility on a large content of pentane.

In carrying out-the process of this invention we may employ a distillatedirectly from the cracking operation, containing both lighter andheavier hydrocarbons than desired in the gasoline. In

this case it is preferred to carryout the fractionation for theseparation of butane and pentane under higher pressures than thosedescribed and eliminate the propane in the same operation as used toseparate butane and pentane. In this case it is also convenient toemploy a single fractionating column and. remove the butane from a sidestripper, much as shown for removal of pentane in the apparatusdescribed herein. The wild gases, including propane and ethane, may alsobe rejected along with some butane to be later recovered by anabsorption process from which the butane is fractionated from thepropane and returned to the system. Where the pressure distillatecontains hydrocarbons boiling above the desired end point, these'areeliminated by a redistillation of the gasoline. This may be accomplishedby flash evaporation of the stock flowing from the bottom of thefractionating tower and distillation of the remaining unevaporated stockto obtain the desired end point. This unevaporated stock may be treatedwith sulfuric acid or fullers earth before final distillation for theimprovement of'gum stability, color etc. and

antioxidants may be added to the finished gaso line.

In applying. our process to the operations of a petroleum refinery itwill sometimes "be desirable summer gasoline while in the fall andwinter it' may be desirable to produce winter gasoline only. Under theseconditions we may retain in storage pentane produced in the summergasoline manufacturing operation and draw upon this storage of pentanewhen it is desired to produce winter gasoline or, vice versa we maystore up butane produced in the winter gasoline manufacturing operationand retain it in storage, refrigerated or under pressure, or blended inheavier gasoline stocks until required for use in manufacturing summergasoline. This feature of the process makes it particularly suitable formeeting varying demands of diiferent gasolines and avoids the necessityof carrying large'stocks of one gasoline or the other from one season tothe next where this is not desired, as in the case of a shortage ofstorage capacity@ It should be understood that our invention is notlimited to producing any specific vapor pressure or degree. ofvolatilityin summer and winter gasolines and we do not intend to be limited by theexamples set forth. 'We ordinarily e'mploy our process, however, toproduce winter gasolines having a volatility of between 30 and oil at158 F. and a Reid vapor pressure of between 10 and 16 lbs. The summergasolines produced by our process will ordinarily possess vaporpressures below 10 lbs.Reid and usually between Sand 9 lbs. Reid whilethe percent evaporated at 158 F. will usually be from 7 to 18%. Thevolatility of the winter gasoline will always be higher than that of thesummer gasoline and this will be true .of the vapor pressure also.

We claim: I

1. The process of producing winter 'and'summer gasolines from a singlegasoline supply of relatively unvarying composition, comprisingfractionating a portion of said supply gasoline to remove therefrom afraction rich in pentane hydrocarbons and produce a gasoline deficientin pentane hydrocarbons but suitable for summer gasoline requirementscharacterized by hav ing a ratio of pentanes to butanes less than 1 andmorethan 0.11 and a volatility of between about "I and 18%oif at 158 F.,and combining said pentane-rich fraction with a further quantity of saidsupply gasoline to produce a gasoline having a higher concentrationofpentane hydrocarb ons'suitable for winter gasoline require-' ments.

2. A motor fuel adapted for use in warm weather comprising a mixture ofhydrocarbons boiling within the gasoline boiling range and containinghydrocarbons of the aliphatic series beginning with butane and pentaneand substantially free from propane contamination, characterized byhaving a ratio of pentane hydrocarbons to butane hydrocarbons less thanone and more than 0.11 and between about 7 and 18 percent evaporated at158 F. v

3. The process of producing from a single supply of gasoline ofunsuitable volatility and vapor pressure characteristics for eithersummer or winter use, a winter gasoline having a vapor pressure ofbetween 10 and 16 pounds Reid and a percent-evaporated at'158" F.between 30 and 45 and a summer gasoline having a vapor pressure abetween 6 and 10 pounds Reid and a percent evaporated at 158 F. ofbetween '7 and 18, and further characterized by having a ratio ofpentanes to butanes less than 1 and more than 0.11 comprising removingpentane hydrocarbons from a 4. The method of producing satisfactorysummer winter gasoline from a single gasoline supply of relativelyconstant composition but un-' suitable for either summer or winter usebecause 'ofexcessive 'vapor pressure for summer and insufiicientvolatilityfor winter, comprising removing pentane from one portion ofsaid gasoline supply to reduce the pentane content substantially belowthe content of butane thereof, and incorporating said, pentane inanother portion of said 7 adapted for summer gasoline requirements,comprising a petroleum hydrocarbon distillate boiling within thegasoline boiling range having a volatility of about 7 to 18% oil at 158F. and

' containing fractions boiling within the range of butanes and pentanes,the amount of said butane wfraction exceeding the amount of said pentanefraction by from 1.9 to 9% of said total gasoline. 6. A motor fueladapted for use in warm ieathercomprising a mixture of hydrocarbonsboiling within the gasoline boiling range and containing hydrocarbons ofthe'aliphatic series beginning with butane and pentane andsubstantially'free from propane contamination, characterized by having aratio of pentane hydrocarbons to butane hydrocarbons within the range ofabout 0.14 and 0.76. and further characterized by a volatility betweenabout '7 and 18% evaporated sit-158 r.

, 7. In the process-of producing gasoline havingvolatilitycharacteristics suitable for summer use,

from a supply gasoline of substantially uniform composition, thestepswhich comprise removing from said supply gasoline a fraction comprisingchiefly hydrocarbons of the butane boiling range,

and a separate fraction comprising chiefly hyd'rocarbons of thepentane-boiling range, leaving a blending stock deficient in bothbutanes and pentanes, andcombining amounts of the butane boiling rangefraction with said'blending stock to give'a product for use as a'summergasoline -having a Reidflvapor pressure of about 6 to 10 pounds, avolatility of about '7 to 18% 011 at 158 F. and a ratio ofv pentanes tobutanes less than 1 and more than 0.11.

8. In .the "process of producing gasolines of. widely difleringvolatility characteristics and suitable for winter use and simmer userespectively, from a supply sasoline of substantially uniformcomposition but having volatility characteristics which as such are notbest designed 'for particular climatic conditions, the steps whichcomprise removing front said gasoline a fraction comprising chieflyhydrocarbons of the'butane boiling range, and a separate fractioncomprising ehiefly hydrocarbons of the pentane boiling range, leaving ablending stock deficient in'both butane and pentane, combining amountsof the butane boiling range fraction with said blending stock to give aproduct having a ratio of 7 to18 ofl' at 158 marmas a summer gasoline,and combining said pentane boiiingrange fraction with supply gasolinewhereby a winter gasoline is produced which contains more pentanepentanes to butanes less than 1 and moretnan 0.11, said product having aReid vapor pressure of about 6 to '10 pounds and a volatility of-aboutwinter gasoline,

boiling range hydrocarbons than are contained in the supply gasoline. I

9. The process of preparing from a supply gasoline a summer motor fueland a winter motor fuel having desired volatility characteristics, whichcomprises the .steps of removing from said gasoline two fractions ofhydrocarbons, one

of which contains a relatively high concentration tration of pentane andseparately collecting said fractions, combining a portion of thefraction relatively high in pentane with a partly debutanized gasolineto prepare said winter motorfuel, and combining a sufllcient amount ofthe fraction relatively high in butane with a portion of the partiallydebutanized and depentanizedgasoline to produce a summer motor fuel witha ratio of pentanes to butanes less than 1 and more than 0.11, and avolatility of between about 7 and 18% off at 158 F.

" 10. The process of producing two grades of gasoline from a gasolinesupply of substantially uniform composition, one of said grades ofgasoline being adapted for use as a summer motor fuel, having a ratio ofpentanes to butanes less than 1 and more than 0.11, and a volatility of.betweenabout"! and 18% oil? at 158 F. and the other being adapted as awinter motor fuel, having a higher proportion of pentanes than butanesand a higher concentration of pentanes thanv thatv of theoriginal'supply gasoline, comprising separating from said supplygasoline a fraction -boiling predominantly within the range of hutanes,further separating from said supply gasoline a fraction boilingpredominantly within the range of pentanes, and leavinga plurality ofgasoline stocks, one of which is deficient in pentanes, combiningsaidgasoline stock deflcientinpentanes with said predominantly butanefraction to produce said summer grade of gasoline and combining anotherof said gasoline stocks with said predominantly pentane fraction toproduce said 11. In the process of adapting the pressure distillateproduced by a cracking plant to the varying volatility requirements ofwinter and summer motor fuels having a Reid vapor pressure between about10 and 16 pounds and a volatility of pressure between about 6 and 10pounds and a volatility of about '7 to 18% of! at 158 F. respectively,the steps which comprise forming debutanized and depentanized pressuredistillate from the pressure distillatesupply, a fraction .rich inhydrocarbons boiling within the range I of butane, and a fraction richin hydrocarbons boilingwithin the range of pentane, adding sufficientquantities of the fraction rich in hydrocarbons boiling within therangeof butane to some of the debutaniz'ed and depcntanized pressuredistillate to produce a summer gasoline of the desired volatilitycharacteristics and havin of butane and the other a relatively highconcenabout 30 to oil at 158 FQand a Reid vapor a ratio of pentanes tobutanes less" than 1 and more than 0,11, and adding suilicientquantities of the fractionrich in hydrocarbons boiling withnized andundepentanized pressure distillate supply to produce a winter gasolineof the desired volatility characteristics. I 12. In the process ofadapting the pressure sure of about 10 to 16 pounds and a volatility 01"about 30 to 45% off at 158 F. and a Reid vapor 7'0 distillate producedby a cracking plant to thev varying volatility requirements of a winterand asummer motor'fuel having a Reidvapor presin the pentane range tosome of the undebuta- I a pressure ot'about 6 to 10 pounds and avolatility of about 7 to 18% oil at 158 F. respectively, the steps whichcomprise forming a partially debutanized traction and a partiallydepentanized fraction from the pressure distillate supply, a fractionrich in hydrocarbons boiling within the range of butane, and a fractionrich in hydrocarbons boiling within the range of pentane, addingsuflicient quantities of the fraction rich in hydrocarbons boilingwithin the range of butane to the partially depentanized pressuredistillate supply to produce a summer gasoline of the desiredvolatilitycharacteristics having a ratio of pentanes to butanes less than 1 andmore than 0.11, and addingsuflicient quantities of the fraction rich inhydrocarbons boiling within the pentane range to the partiallydebutanized pressure.

distillate to produce a winter gasoline of the desiredvolatilitycharacteristics.

13. The method of making seasonal gasolines from a supply gasoline ofsubstantially constant composition which comprises making a summergasoline of abnormally high vapor pressure with respect to itsvolatility by removing a suflicient amount of the fraction boilingwithin the range of pentane from gasolines marketed in the summer seasonwithout appreciably affecting the butane content thereof, said summergasoline being characterized by a volatility of between about 7 and 18%oi! at 158 F. and a ratio or pentanes to butaiies less than i and morethan 0.11, and blending said removed pentane fraction with said supplygasoline of substantially constant composition to make a winter gasolinecharacterized by abnormally high volatility with respect to its vaporpressure.

14. The process of manufacturing gasoline suitable for summer and winteruse from the products of a cracking operation containing gasoline andhydrocarbon gases undesirable in the gasolines, comprising eliminatingsaid undesirable hydrocarbon gases together with butane, recovering saidbutane by an absorption process, separating from said products a portionof the gasoline from which pentane has not been removed, a hydrocarbonfraction boiling predomi antly within the range of pentanes and aportion of gasoline from which pentane has been removed, adding saidrecovered -.butane to said portion of gasoline from which pentane hasbeen removed to produce a summer gasoline having a ratio of pentanes tobutanes less than 1 and more than 0.11, and having a volatility of about7 percent to 18 percent evaporated at 158 F., and adding said pentanefraction to a portion of the gasoline from which pentane has not beenremoved to produce a winter gasoline.

JQSEPH K. ROBERTS. MORRIS T. CARPENTER.

